A STUDY OF THE RELATIONS BETWEEN CHLOROPLAST PIGMENTS AND DRY WEIGHTS OF TOPS IN DENT CORN

Abstract

Leaf area, dry wt. of tops and chloroplast pigment content were determined in corn plants grown in the greenhouse, using sand cultures with culture solutions added by the constant drip method, and in the field. Chloroplast pigment measurements failed to show a proportional relation to the measured growth rates of a given strain, no matter whether expressed on the basis of pigment per 100 sq. cm. of leaf area or per gm. of leaf (dry wt.). The strain which showed high chlorophyll and carotin concentrations per unit of leaf area also had high average rates of increase in dry wt. of tops, and vice versa. Xanthophyll values were variable and showed no definite relation to rates of growth. Chlorophyll was more closely correlated with leaf area than with dry wt. of leaves. Carotin and xanthophyll, however, were not as closely correlated with leaf as with drywt. of leaves. There was a close correlation between the total quantity of chlorophyll contained in the leaves of the various strains of maize and their dry wt. of tops at successsive harvests. Correlations between total carotin content and dry wt., and between total xanthophyll content and dry wt. were close enough to be significant but were not as exact as those noted between total chlorophyll content and dry wt. The average ratios between total chlorophyll and dry wt. of tops were practically identical with all 3 strains of corn. Ratios between dry wt. and carotin content were more variable than those noted between dry wt. and chlorophyll, but a certain constancy was apparent. Ratios between dry wt. and xanthophyll are so variable that their significance is doubtful.